I usually go thru an entire water bottle in 10-12 miles when the temperatures are high like you posted.
Protein shakes are great starters but as your distance increases you'll want carbs for energy. You'll still lose weight eating carbs. I carry a few Gu gels or a Hammer bar for longer rides. As your mileage increases you'll be able to determine how many gels or bars you'll want to take with you. I always take extra in case I decide to add a few extra miles to my rides.